Spatio-temporal analysis and simulation of urban ecological resilience in Guangzhou City based on the FLUS model

Prediction of urban ecological risk, which is increasing with the rapid development of China’s economy, has become more complex and difficult, resulting in great damage to the safety of people’s lives and property and the quality of the ecological environment. Elucidation of the change mechanism of the urban ecological resilience level from the perspective of the resilience characteristics and exploration of the spatiotemporal differences of the urban ability are necessary to prevent and resolve ecological risks. To this end, here, a model for the evaluation of urban ecological resilience was constructed by considering three aspects: resistance, adaptability, and resilience. The spatiotemporal change pattern of urban ecological resilience in Guangzhou from 2000 to 2020 was evaluated. Furthermore, a spatial autocorrelation model was used to explore the management model of Guangzhou’s ecological resilience in 2020. Finally, based on the FLUS model, the spatial pattern of urban land use under the 2035 benchmark and innovation- and entrepreneurship-oriented scenarios was simulated and the spatial distribution of the ecological resilience level under different urban development scenarios was evaluated. We found that from 2000 to 2020, areas with a low ecological resilience expanded to the northeast and southeast, whereas areas with a high ecological resilience significantly decreased; from 2000 to 2010, original high-level regions in the northeast and east of Guangzhou were transformed into medium level regions. Further, in 2020, the southwestern region of the city will show a low level of resilience and high density of pollutant discharge enterprises, indicating that the ability to prevent and resolve environmental and ecological risks in this region is relatively low. Additionally, the overall ecological resilience of Guangzhou under the innovation- and entrepreneurship-oriented “City of Innovation” urban development scenario is higher than that under the benchmark scenario in 2035. The results of this study provide a theoretical basis for the development of resilient urban ecological environment.

Over the past 40 years of economic reforms known colloquially as the "reform and opening up" of China, Chinese cities have become larger and stronger. Accordingly, interactions between natural, human, and various other unpredictable factors have increased, with the conflict between humans and land becoming increasingly acute. Research investigating ecological resilience has unique advantages in solving various problems faced by cities, while also being an important method of coordinating the relationship between humans and land. Resilience research, particularly including research into the resilience of urban subdivisions, is conducive to the sustainable development of cities. In recent years, with the promotion of the construction of ecological civilization and the development of energy conservation and environmental protection technology, China's ecological resource output capacity has been continuously enhanced. Furthermore, the utilization of resources, industrial investment, and scientific and technological development have been developing to maximize added value while minimizing resource consumption 1 . Meanwhile, several cities have increased ecological output and economic efficiency, while also contributing to massive resource consumption and serious environmental pollution, among other problems, in addition to damaging the resilience of their local ecological environments. In the face of a series of crises caused by globalization, urbanization, and ecological vulnerability, urban ecological resilience, an important dimension of urban resilience assessment, has begun to receive widespread attention from academia and society. Therefore, understanding how urban ecological resilience levels change from the perspective of resilience characteristics and spatiotemporal differences in urban resilience are necessary to prevent and resolve ecological risks. The existing body of urban resilience research emphasizes the concept of evolutionary resilience, or how resilience shifts over time as a result of design strategies. Godschalk believes that urban resilience is the combination of material systems and human participation, with human participation playing an important role 14 . From the perspective of evolutionary resilience, the evaluation methods of urban resilience in existing studies have similarities and differences, that is, considering the basic functions of urban systems and the social attributes of learning and innovation. Additionally, Jha et al. stated that urban resilience has four main components, namely infrastructure and institutional, economic, and social resilience 15 . In contrast, several scholars have placed more emphasis on the participation of social active subjects. For example, Hudec et al. constructed urban resilience indicators using the three dimensions of economic, social, and community management capabilities, and subsequently evaluated the differences between Slovak cities in coping with the financial crisis 16 ; Campanella focused on the power of human communities and believes that urban resilience is essentially dependent on population clusters 17 . Throughout the existing research on urban ecological resilience, which has been limited by data availability and the unclear definitions of concepts, the focus has been on analysis of the "level" of urban ecosystem in terms of resistance to interference, restoration, and construction. However, discussion on urban ecological resilience from the perspective of evolutionary resilience is lacking, therefore, comprehensively evaluating the essence of an urban ecosystem and its ability to aid in innovation and development is difficult. As an important dimension of urban resilience, the assessment of ecological resilience has also received attention from scholars, but most concerns are based on prevention and control of ecological and environmental risks 18,19 . Few studies consider the spatial changes in urban ecological resilience levels from the perspective of resilience characteristics and neglect the zoning management assessment of ecological resilience and risk, making implementation the results in urban planning applications difficult 20,21 . Secondly, the existing research on urban ecological resilience is mainly based on administrative boundaries, but lacks explanations for its evolution characteristics, spatial correlation, and regional differences, which has certain limitations for scientifically formulating urban construction management policies 22,23 . In addition, research on constructing indicator systems from the perspective of the connotation of urban ecological resilience is relatively rare 24,25 . Taking Guangzhou City as an example, this study considers the spatial change of urban ecological resilience level from the perspective of resilience characteristics and constructs an urban ecological resilience assessment model based on the perspective of evolutionary resilience, with a view to filling the gaps in research on spatial and temporal changes and simulation of urban ecological resilience scenario.
With the rapid development of the national economy, urban ecological risks are becoming more frequent and unpredictable, causing enormous damage to the safety of people's lives and property and the quality of the ecological environment 26,27 . The outbreak of the global COVID-19 pandemic in 2020 placed additional demand on medical-related ecological environment protection (medical waste, among other things) in the short term. In the long term, the gradual recovery of production, life, and the social economy in the post epidemic era will exacerbate the disparity between supply and demand of resources and trigger new urban ecological risks 28,29 . Therefore, improving the ability of cities to cope with ecological risks has become an important direction for achieving sustainable urban development. Strengthening the protection of historical and cultural heritage, shaping the urban landscape, strengthening the renovation of old urban residential areas and community construction, enhancing urban flood control and drainage capabilities, and building sponge cities and resilient cities are all becoming more important urban construction goals 30 . Improving the level of urban governance and strengthening risk prevention and control in the governance of megacities further demonstrates the important role of building resilient cities in China's economy and society. Based on the perspective of evolutionary resilience, urban ecological resilience can be regarded as an inherent attribute always present in urban ecosystems. Regardless of whether urban ecosystems are disturbed or not, they always have the dynamic ability to defend themselves before interferences occur, respond in time when interferences occur, and constantly learn and innovate. Therefore, this study uses the dynamic evolution characteristics of the adaptive cycle model for reference to propose the three-stage capacity of urban ecological resilience, namely resistance, adaptability, and resilience. Additionally, an assessment model for urban ecological resilience was constructed as previously described 31 , considering the basic characteristics of resilience (resistance, adaptability, and resilience). Subsequently, the pattern of spatiotemporal changes in the urban ecological resilience of Guangzhou from 2000 to 2020 was evaluated herein. A spatial autocorrelation model was also used to explore the ecological resilience zoning management model of Guangzhou in 2020. Finally, we simulated the urban expansion of Guangzhou under the 2035 benchmark and innovation-and entrepreneurship-oriented scenarios in addition to evaluating urban resilience, adaptability, www.nature.com/scientificreports/ resistance, and ecological resilience under different scenarios. Based on the results of this simulation, several operable policies and planning suggestions for the construction of ecological resilient cities and industrial spatial layout were suggested.

Study region and data sources
Study region. Guangzhou is the capital of the Guangdong Province and located at 113°17′ E and 23°8′ N in the south of the Chinese Mainland, central south of the Guangdong Province, and on the northern edge of the Pearl River Delta. Moreover, Guangzhou is adjacent to the South China Sea and the Hong Kong and Macao special administrative regions and is known as China's south gate to the world. Guangzhou is a hilly area, with high terrain in the northeast and low in the southwest. There are also mountains in the north and northeast, hills and platforms in the center, and alluvial plains around the Pearl River Delta in the south.
Since the economic reforms, Guangzhou has developed rapidly, with the per capita gross domestic product rising from 25,800 yuan in 2000 to 134,000 yuan in 2020. Over the past 20 years, Guangzhou has also witnessed rapid physical growth, and a large amount of natural land has been occupied, causing several environmental problems, including a decline in the urban habitat quality and ecosystem services alongside a drastic increase in the urban greenhouse effect. When planning the development goals of the "Fourteenth Five-year Plan, " Guangzhou proposed to take precautions against and resolve various risks and challenges with a proactive layout while constantly enhancing the resilience of urban development. Therefore, Guangzhou has great significance as an example of spatiotemporal changes in urban ecological resilience.
Data sources. In this study, remote sensing image data from 2000, 2010, and 2020 were used to obtain a classification through supervised classification and visual interpretation. Remote sensing images were preprocessed using image clipping, atmospheric correction, and geometric correction. Four categories were then obtained by supervision and classification: forestland, cultivated land, water area and wetland, and construction land. The precision test results showed that all kappa coefficients of the classification were > 85%. The list of key pollutant discharge units in Guangzhou was also obtained from the Guangzhou Municipal Bureau of Ecology and Environment, while coordinate information was derived by matching enterprise names and points of interest.

Methods
Construction of urban ecological resilience assessment model. The International Association for Regional Sustainable Development (ICLEI, 2002) defines a resilient city as a city that can resist, absorb, quickly adapt to, and effectively respond to hazards in a timely manner. This focuses on the enhancement of the city's ability to withstand shocks and resilience. A resilient city has three characteristics: resistance, adaptability, and resilience. Compared with the warning characteristics of risks, resilience can be used for pre-assessment or postanalysis. Therefore, based on risk prevention and control management in resilient cities, "twice the result with half the effort" can be achieved. In this study, an assessment model of urban ecological resilience was constructed considering three aspects: resistance, adaptability, and resilience.
Resistance refers to the ability of the urban ecosystem to resist external interference. The results of many previous studies have shown that ecosystem resilience is closely related to the ecosystem service function. The ecosystem service function refers to natural environmental conditions and functions formed by the ecosystem and ecological process to maintain human survival. Costanza et al. divided the conditions and service functions of the global ecosystem into 17 categories 32 . In this study, according to the characteristics of the urban ecological resilience indicator system, and in combination with the concept of urban ecological resilience, the resistance of the ecosystem was considered to have been formed by selecting the values of climate regulation, gas regulation, water conservation, soil formation and protection, and waste treatment, among other regulatory ecosystems (P) based on water, soil, gas, and other media.
The equivalent coefficient of the ecosystem service value was used here to obtain the ecosystem service value coefficient. The equivalent factor of the ecosystem service value is the relative contribution rate of the potential service value of the ecosystem, which is equal to 1/7 of the food value per hectare every year 33 . The equation used for the calculation of the ecosystem service value in Guangzhou is as follows: where ESV is the ecosystem service value; A k is the area of land-use type k; VC fk is the f-th ecosystem value coefficient of land-use type k, which is derived from several ecosystem service value coefficients of land-use types in the Pearl River Delta 34 . The more stable an ecosystem, the higher its adaptability (A) 35 . Therefore, in this study, relevant indicators of the ecosystem landscape structure stability were used to express its adaptability. The stability of the landscape structure of an ecosystem is dependent on the stability of landscape pattern organization related to spatial heterogeneity and landscape connectivity. The landscape index was also used to evaluate landscape stability based on landscape heterogeneity and connectivity. The landscape index reflects the spatial pattern of the ecological landscape and has been widely used in landscape ecological zoning, planning, monitoring, prediction, and impact assessment, leading to the targeted and timely regulation of landscape ecological spaces 36,37 . Landscape heterogeneity and connectivity describe two aspects of the landscape structure of an ecosystem, which are irreplaceable. Therefore, their weights can be assumed to be equal. Specific indicators are listed in Table 1.
The resilience of the ecosystem can also be called ecological resilience, which reflects the ability and potential of the ecosystem to recover from damage 38 . When encountering external pressure (e.g., climate or geological disasters), it is easier for land use types close to natural ecosystems to recover, whereas man-made construction where R is the ecosystem resilience, A k is the land use type, and the ecological resilience coefficient of land use type k is obtained from Peng et al. 39 .
In addition, resistance, adaptability, and resilience all have different units. Therefore, data standardization is necessary when using multiple indicators for the evaluation. In this study, the three aspects were standardized to the interval [0, 1]. The equation for calculating the toughness level is as follows: where A is the adaptability, P is the resistance, and R is the resilience. Spatial autocorrelation model. Exploratory spatial analysis includes global and local spatial autocorrelation analysis. Global and local spatial autocorrelation can be used to describe the spatial characteristics of geographical observations throughout an entire region and the spatial correlation and differences between the study area and adjacent areas, respectively [40][41][42] .
The purpose of global spatial autocorrelation analysis is to determine whether a variable is spatially related in addition to its relevance. Spatial autocorrelation coefficients are often used to describe spatial dependence quantitatively. Specifically, the spatial autocorrelation coefficient is used to measure the spatial distribution characteristics of physical or ecological variables and their effects on the field. If the values of a variable become more similar as measurement distance decreases, the variable is positively correlated to space. However, if the measured values diverge as distance decreases, the spatial correlation is considered negative. If the value shows no spatial dependence, the variable shows spatial irrelevance or randomness. There are several types of spatial autocorrelation coefficients, which are each suitable for different data types. Spatial autocorrelation analysis is widely used in the discipline of geographic statistics; the most important among the several available indices are Moran's I coefficient and Geary's C coefficient. In this study, Moran's I value was used to analyze the global spatial evolution characteristics of the urban ecological resilience of Guangzhou, and the Euclid distance criterion was selected to construct the spatial weight matrix. The formula is as follows: Among them, the significant performance of Moran's I value passes the Z score test: n is the number of study areas, x i and x j are the observations of the ith and jth study areas respectively, while W ij is the spatial weight matrix. The value range of global Moran's I is [− 1, 1]. On the premise of passing the significance test, I > 0 represents a positive spatial correlation, and the spatial distribution pattern is a gathering situation; I < 0 indicates negative spatial correlation, and the spatial distribution pattern is decentralized; I = 0 means there is no spatial correlation, and the spatial distribution pattern is random. In the formula (5), E (I) is the expectation index and Var (I) is the variance. If Z < − 1.65 or Z > 1.65, it means that the spatial distribution is relevant through the significance test.
The local spatial autocorrelation is to analyze the heterogeneity of spatial distribution of geographical element observations in the local study area. The Getis-Ord G * i index is selected to analyze the local spatial evolution characteristics of epidemic network attention through the regional changes of geographic elements' spatial cold and hot spots. The formula for this is: where n is the number of study areas, W ij is the spatial weight matrix, and X j is the observation value of study area j. On the premise of passing the significance test, if G * i is positive, it is the high-value cluster area, namely the hot spot area; If G * i is negative, it is the low-value concentration area, namely the cold spot area. www.nature.com/scientificreports/ Geodetector. Geographic detectors are statistical methods used to detect spatial differentiation and reveal driving factors. The core idea assumes that if an independent variable affects a dependent variable, the spatial distributions of the independent and dependent variables are similar. Geographic detectors include the following four detectors: Differentiation and factor detection: Detect the spatial differentiation of Y; And the extent to which a factor X can explain the spatial differentiation of attribute Y. Measured by q value, the expression is as follows: where h represents the stratification of variable Y or factor X, i.e., classification or partition; Nh and N represent the number of units in layer h and the whole region, respectively; σ 2 h and σ 2 represent the variance of layer h and the value of Y in the whole region, respectively; and SSW and SST represent the sum of variance in the layer and the total variance in the whole region, respectively. The range of q is [0,1].
Interaction detection: identify the interaction between different X factors, that is, evaluate whether the explanatory power of X1 and X2 on dependent variable Y increases or decreases, or whether the influence of these factors on Y is independent.
Risk area detection: judge whether the attribute mean value between two sub areas is significantly different, and test with t statistics: wherein Y h represents the attribute mean value in sub-region h, n h represents the number of samples in subregion h, and Var represents the variance.
Ecological test: compare whether two factors X1 and X2 have significant differences in the impact on the spatial distribution of attribute Y, and use F statistics to measure: wherein N x1 and N x2 represent the sample size of the two factors, SSW X1 and SSW X2 represent the sum of the intra-layer variances of X1 and X2, respectively, and L1 and L2 represent the number of X1 and X2 layers, respectively.
Urban land-use change model. The Future Land Use Simulation (FLUS) model is based on the development of GeoSOS software (GeoSOS2.0.0a, URL: https:// geosi mulat ion. cn/) and primarily combines an artificial neural network (ANN) algorithm, adaptive inertia, and competition mechanism to improve the traditional cellular automata (CA) model, which is more suitable for multi-land scenario simulation 43,44 . The FLUS model includes two main aspects: ANN and adaptive inertial competitive CA 45 . The ANN estimates the possibility of each land-use type on each cell grid through training samples, whereas adaptive inertia and the competition mechanism can be used to deal with the interaction between land-use types. The FLUS model has been widely used for the previous simulation of urban land-use expansion.
In this study, two scenarios, the benchmark and the innovation-oriented "City of Innovation" scenarios, for the urban expansion of Guangzhou in 2035 were simulated. The GeoSOS-FLUS software was also used to simulate the land-use patterns of the FLUS model.
Based on the land-use changes between 2010 and 2020, the benchmark scenario adopted the land-use scale predicted by the original land-use transfer matrix and integrated the analysis and exploration of other studies on driving factors of land-use change, as well as factors that actually affect the urban development of Guangzhou in the planning process. Finally, social economy, natural conditions, traffic conditions, and driving factors were selected as planning factors ( Table 2).
The "City of Innovation" concept was derived from the future urban positioning of Guangzhou proposed in the "Fourteenth Five-year Plan" for Scientific and Technological Innovation of Guangzhou in 2022, which was "to become a leading site for major scientific discoveries and technological inventions worldwide, a model city for international science and technology to enable old cities to have new vitality, and a highly attractive, high-level, open and innovative city. " The "City of Innovation" scenario is an innovative industrial development perspective, with relatively strict farmland protection. Compared with that in the benchmark scenario, the proportion of farmland converted into construction land in this scenario is decreased by 15%. In addition, the "City of Innovation" scenario adds innovation drivers (Table 2). Based on the "Fourteenth Five-year Plan" for the Development of Guangzhou's Strategic Emerging Industries, relevant planned manufacturing innovation www.nature.com/scientificreports/ centers and major industrial platforms can be extracted, and the distance between each grid and the innovation center and the major industrial platforms is calculated and assigned to obtain the driving factors of Guangzhou's innovation center and major industrial platforms. Finally, the above-mentioned innovation factor driving layer was used in this study as an additional factor, considering innovation in industry development. This was input into the ANN, with the suitability of the probability layer being calculated, and the land-use spatial pattern being simulated considering innovation industry development.

Results
Spatiotemporal changes in urban ecological resilience of Guangzhou. Figure 1 shows the spatiotemporal changes in the urban ecological resilience level of Guangzhou every 10 years between 2000 and 2020. The total level of urban ecological resilience decreased over time. Based on the grid level, its average value decreased by 32.86%, while the highest value decreased by 20.27%, and the standard deviation decreased by 34.33%. From the perspective of spatial distribution, regional differences in the ecological resilience levels of Guangzhou in 2000 were not significant. Most of the regions exhibited medium and high ecological resilience, whereas areas with low ecological resilience were distributed throughout the southwest of the city in addition to the northwest and southwest of the central area. With urban expansion, areas with low ecological resilience expanded into the southeast and south in 2010, while areas with high values, which were originally continuously distributed within the southeast, became scattered. Due to the overall lack of relatively appropriate planning and arrangement, the township enterprises in the Huangpu District of the southeast developed rapidly. Most of these factories were scattered on a small scale, occupying large amounts of natural resources, reducing ecological service functions, and increasing landscape fragmentation, which ultimately resulted in a significant decline in resilience. In addition, the south of the city is located close to the Pearl River Estuary, with a large number of high-quality wetland resources. The excessive reclamation of the south has greatly damaged the natural ecological landscape. In 2020, the overall ecological resilience level of Guangzhou was intermediate. Regions with higher levels were only distributed within the northeast and east regions of the city. Original high-resilience regions in the southeast instead displayed an intermediate level. Additionally, rapid land urbanization has converted a large amount of cultivated land and forestland, as many rural migrant workers entered the city and increased housing demands. Part of the cultivated land has been occupied and transformed into construction land, further aggravating the severe challenge of insufficient cultivated land resources.
The spatiotemporal changes in the ecological resilience level of Guangzhou from 2000 to 2020 were similar to those obtained in previous relevant studies in Shanghai, Beijing-Tianjin-Hebei, and other cities. With development and urbanization, the overall distribution of ecological resilience levels is gradually decreasing around urban centers and areas with low resilience levels consolidate from scattered to continuous distributions. Although Guangzhou differs from Shanghai, Beijing-Tianjin-Hebei, and other cities in terms of transportation and economy, the early "pie sharing" urban expansion mode of cities in China tends to converge. This extensive urban expansion mode led by the construction of industrial parks has led to the occupation of a large amount of high-quality cultivated land around the city. Although the policy of "balance between occupation and compensation of cultivated land" in the later stages of development has guaranteed a minimum of 1.8 billion mu (1 mu = 666.7 m 2 ) of cultivated land on the surface, the phenomenon of "exploit the advantages and compensate for the disadvantages" often occurs in local practical operations and has led to the encroachment on a large number Table 2. Driving factors of urban land use change.

Category
Data Weight assignment

Socioeconomic Population
The data of the real population (permanent population + temporary population) in 2020 is used as the driving factor to calculate the population core density in the study area of Guangzhou, which is used as the driving layer Public service facilities and commercial service facilities Select education and training, medical care, cultural media, sports and fitness, government agencies and other categories as public service facilities POI, calculate their core density, and take it as the driving layer of public service facilities Take finance, food, hotel, shopping, leisure and entertainment as business service facilities POI, calculate its core density, and take it as the driving layer of business service facilities Natural condition

Altitude
The elevation is processed inversely and normalized to obtain the elevation driven layer Slope Assign values according to the grade of slope, and then conduct normalization to obtain the slope driving layer

Rivers
The distance layer from each grid to the nearby river system is established through European distance calculation, and then normalized to obtain the driving layer In this study, ArcGIS10.2 was used to analyze the nuclear density of key pollutant discharge units in Guangzhou, while Geoda was used to analyze the resilience level and density of pollutant discharge enterprises with univariate and bivariate spatial autocorrelation analysis. The results of these analyses are shown in Fig. 2. The spatial autocorrelation analysis of the resilience level (Fig. 2) showed that areas with low ecological resilience were distributed throughout the west and southwest of the city, whereas areas with high values could be observed in the east, northeast, and southeast of the central area. In recent years, the government has invested a substantial amount of money in improving the wetland quality of Haizhu Park in the south of the city near the Pearl River Estuary and in the city center. Wetland ecological resources can block the effects of adverse factors and disasters by playing the role of an ecological barrier, which significantly improves ecological resilience while preventing and resolving ecological risks. The results of the bivariate spatial autocorrelation of the urban ecological resilience level and pollutant discharge enterprise density showed that the southern region of the city had a low resilience level alongside a high polluting enterprise density cluster distribution (Fig. 2), which was closely related to the urban strategy of Guangzhou's overall southward development. The southern part of Guangzhou is flat and close to the Pearl River Estuary. Transportation is convenient, considering the presence of Shenzhen, Dongguan, and other core cities within the Pearl River Delta, thus leading to the formation of the Dawan District industrial cluster. Moreover, the transfer of traditional manufacturing industries, mainly printing and dyeing, from the surrounding cities has begun. The development of industrial clusters has driven the expansion of construction land in the southern region, encroaching on the surrounding ecological land resources, fragmenting the patches of ecological land, and reducing the level of ecological resilience in the region. The low resilience coupled with www.nature.com/scientificreports/ the high density polluting enterprises suggests that the environmental pollution risk is relatively high, with a low capacity for prevention and resolution. Therefore, increasing investment in environmental monitoring and ecological governance in this region to prevent major environmental pollution events is necessary.  (Table 3). In 2000, the Moran's I indices of adaptability, resistance, resilience, and urban ecological resilience in Guangzhou were 0.129, 0.138, 0.147, and 0.132, respectively. Additionally, all P values were ≤ 0.001, while the Z values were greater than 1.96, demonstrating significance. A positive spatial autocorrelation was also observed; however, the Moran's I indices ranged from 0.1 to 0.2, suggesting that the aggregation of spatial autocorrelation was not significant. In 2020, the Moran's I indices of resistance, adaptability, resilience, and urban ecological resilience were 0.529, 0.538, 0.571, and 0.583, respectively. The P value was ≤ 0.001 and the Z value was greater than 1.96, indicating significance. A positive spatial autocorrelation relationship and relatively significant spatial agglomeration feature were ultimately obtained. The LISA aggregation map shows that the urban ecological resilience of Guangzhou City in 2000 had high-low clustering characteristics in the southwest, non-confidence characteristics in the northeast, low clustering characteristics throughout the whole southern region, and high-low clustering characteristics in point distribution. High-high clusters did not occur frequently in 2000 but were found scattered within the central region. In contrast, in 2020, the urban ecological resilience of Guangzhou still showed non-confidence characteristics in the northeast, whereas discrete high-low clusters changed to concentrated high-low clusters in 2000 throughout the whole southern region, while scattered high-high clusters were widely distributed (Fig. 3).

Analysis of factors affecting geographical detectors.
Based on the above-mentioned analysis, the driving factors of land-use types in Guangzhou were constructed. Considering the analysis of the nuclear density, linear density, and European distance, the following influencing factors were obtained: population, public service facilities, commercial service facilities, elevation, gradient, rivers, roads, urban roads, transportation facilities, stations, and innovative industries. Urban ecological resilience was used as the independent variable, while indicator data were discretized using the natural breakpoint method. The influence levels of different  www.nature.com/scientificreports/ factors were calculated using the geographic detector model (Fig. 4). From the perspective of driving factors of land-use types in Guangzhou, river distance (0.89) had the highest statistical q value affecting urban ecological resilience, and elevation (0.79) had the second highest q value. This finding showed that natural factors were important influences on urban resilience. The q value of innovative industry (0.72) occupied third place, indicating that such industry also played an important role in the stability, resistance, and resilience of the whole city.  www.nature.com/scientificreports/ Scenario simulation of ecological resilience in the context of urban expansion. In this study, the spatial pattern in 2035 was simulated based on the urban land-use data of Guangzhou from 2010 to 2020. The land-use transfer during this 10-year period is shown in Table 4. From 2000 to 2020, the scale of forestland and construction land remained relatively stable, since converting these into other land types is difficult, whereas converting cultivated land and water area to other land types is relatively easy. Cultivated land was the main source of construction land, accounting for 70.49% of the total transfer to construction land. In addition, the transfer of water area to cultivated land accounted for 68.52% of the total transfer to cultivated land, which was closely related to the wetland reclamation in southern Guangzhou. Figure 5 shows the urban land-use spatial pattern obtained for Guangzhou in 2035 based on the FLUS model simulation. This figure also reveals that, in the benchmark scenario, the construction land in 2035 was marginal in the suburbs of the main urban area and did not show a notable concentration, representing an expansion mode similar to that of the "big cake" city.
The "City of Innovation" scenario is a compact growth model, with construction land mainly growing in the west and south of the city. Figures 6 and 7 show the spatial distribution level of Guangzhou's ecological resilience under the innovation-and entrepreneurship-oriented "City of Innovation" and benchmark scenarios, respectively. Compared with that in the benchmark scenario, the overall ecological resilience of Guangzhou under the urban development scenario ("City of Innovation") was higher. Considering the three aspects of resistance, www.nature.com/scientificreports/ adaptability, and resilience, the difference between the two resilience levels was minimal, whereas the levels of resistance and adaptability in the "City of Innovation" scenario were significantly higher than those in the benchmark scenario. Under the benchmark scenario, adaptability exhibited a notable regional differentiation, showing a decreasing trend from the four sides to the center. The polarization phenomenon was relatively clear, with a significant low-value agglomeration observed in the central urban area, while spatial differences in adaptability levels in the "City of Innovation" scenario were not large, with no significant low-value agglomeration www.nature.com/scientificreports/ occurring. This difference was related to the urban expansion mode of the two scenarios. The "City of Innovation" scenario was a more compact and infilled urban growth mode, whereas the urban growth of the benchmark scenario occurred marginally, in the suburbs of the built-up area. Although such edge expansion could improve landscape diversity and heterogeneity, it would also increase fragmentation and reduce landscape connectivity.
In the design of the adaptability index system in this study (Table 2), the weight of landscape fragmentation (0.5) was greater than that of landscape diversity (0.25), since various landscape types infiltrate each other in www.nature.com/scientificreports/ the late stage of rapid urbanization and small patches of construction land gradually exhibit a landscape pattern dominated by construction land. The landscape diversity would then decrease, whereas this stable state would have no effect on the improvement of adaptability.

Conclusions and discussion
Conclusions. In this study, an assessment model for urban ecological resilience was constructed considering three aspects: resistance, adaptability, and resilience. The pattern of spatiotemporal change in the urban ecological resilience of Guangzhou from 2000 to 2020 was subsequently assessed. Furthermore, the spatial autocorrelation model was used to explore the governance model of Guangzhou's ecological resilience in 2020. Finally, based on the FLUS model, the spatial pattern of urban land use under the 2035 benchmark and innovation-and entrepreneurship-oriented scenarios were simulated, and the spatial distribution of ecological resilience levels under the different urban development scenarios was evaluated. As a result, the following conclusions are summarized: (1) In general, the urban ecological resilience level of Guangzhou decreased from 2000 to 2020. At the grid level, the average value decreased by 32.86%, while the highest value decreased by 20.27%, and the standard deviation decreased by 34.33%, thus indicating that more grids were clustered at low values. From 2000 to 2020, areas with low urban ecological resilience throughout the whole region changed from a scattered to a planar distribution. Additionally, from 2000 to 2010, areas with low ecological resilience expanded into the southeast and south, which was closely related to the excessive reclamation of wetlands in the south and the expansion of construction land. Furthermore, from 2010 to 2020, originally high-level areas of ecological resilience in the southeast of Guangzhou were transformed into medium-level areas. Expansion into a large number of high-quality forest ecological resources in this area was an important reason for this change.
(2) With respect to the spatial distribution, areas with low ecological resilience were concentrated in the middle and southwest of the city in 2020, whereas high-value areas were distributed throughout the east, northeast, and southeast of the central area. The bivariate spatial autocorrelation results of the urban ecological resilience level-polluting enterprise density showed that the southwestern region of Guangzhou had a significantly low resilience level and high polluting enterprise density, which indicated that the environmental pollution risk in this region was relatively high, while the ability to rely on the resilience of the ecosystem itself to prevent and resolve risks was relatively low. (3) Compared with that of the benchmark scenario, the overall ecological resilience of Guangzhou in 2035 was higher under the urban development scenario ("City of Innovation"), with more compact urban growth. Although the difference in the resilience between the two scenarios was not significant, the levels of resistance and adaptability in the "City of Innovation" scenario were significantly higher than those of the benchmark scenario.
Discussion. The concept of resilience originates from natural science. With the increasing attention from the academic community on global environmental change, natural resource depletion, climate warming, and other complex issues, this term has been introduced into social science research. Although enlightening, the concept of resilience applied in the context of social science is endowed with more complex social impacts (such as ethics and power relations) and therefore requires a more comprehensive understanding and explanation. The theory of urban ecological resilience has provided a useful reference for the innovation of urban and rural governance models in addition to promoting interdisciplinary governance research. This interdisciplinary research has since expanded from its initial focus on sociology and ecology into more natural and social sciences, thus providing a new theoretical perspective and practical model for urban and rural governance. Although the combination of the two is very important, applying the theory of urban ecological resilience to urban and rural governance is also difficult. The biggest challenge to this is that urban ecological resilience is often regarded as a heuristic idea and theoretical framework, lacking clear causal relationships, measurement indicators, and evaluation systems, making it difficult to quantify and operate in practice. In addition, urban ecological resilience emphasizes the impact of cross-scale dynamics, although the specific practice is often only targeted at local/local scale interventions. This is actually a methodological issue of resilience and urban and rural governance, which needs to be further explored. In the face of significant changes that have not been observed over the last century, or even a 1000 years, urban and rural governance with resilience as the core represents not only a theoretical frontier, but also an important practical proposition that is worth exploring. Based on the above-mentioned research results, the following three suggestions can be suggested for the construction of Guangzhou as an ecological resilient city: (1) Promote the balanced development of the city, strictly control wetland development, strengthen the reconstruction of and the quality and quantity of ecological land, and improve the overall resilience of the city. Guangzhou should coordinate the development of resources throughout the region, avoid the formation of landscape pressure and urban sprawl in the central city, limit the reduction of ecological resilience caused by excessive concentration, and share development opportunities. In addition, Guangzhou is located close to the Pearl River Estuary and has many wetland resources. The reclamation of wetlands in the southeast of the city should be avoided, while the reconstruction of the wetland landscape should be strengthened. Additionally, further encroachment by urban construction land on wetland resources in the central urban area of the city should be avoided, and ecological land should be protected. The key aim is to maintain the www.nature.com/scientificreports/ integrity of the Nansha and Haizhu wetlands, which play vital roles as ecological barriers, blocking adverse factors and disasters. (2) Implement the zoning management mode of urban environmental and ecological governance: the central and southwest regions of low ecological resilience have a limited capacity for dealing with environmental and ecological risks. In future land and space planning, differentiated urban ecological resilience spatial patterns should be eliminated by strengthening the protection and construction of ecological space in this region. The southwestern region shows a significantly low level of resilience. In areas with high concentrations and distributions of polluting enterprises, high-pollution enterprises must be moved, the upgrading of local industries should be accelerated, and the monitoring of environmental ecological quality in this region must be strengthened to reduce local ecological risks and prevent local risk diffusion from causing global effects. (3) Optimize the development mode of new areas and encourage compact urban development: the eastern part of the city is an important future development space for Guangzhou. The formation of a "pie in the cake" development situation should be prevented, while green landscapes should be vigorously established. In addition, the Guangzhou government should upgrade and transform industry to alleviate population and land pressures within the central urban area, invest more funds in environmental governance and ecological protection under normal conditions, increase the flow of technology and talents, and strive to prevent the ecological resilience differentiation pattern within the city caused by future urban growth. In future urban development toward the east, the Guangzhou government should gradually explore the ecological compensation system with ecological risk transfer as the main body between district and county governments within the city, ease the regional ecological resilience differentiation pattern within the city, and improve the overall ability of the city to prevent and resolve ecological risks.

Data availability
The datasets used and/or analysed during the current study available from the corresponding author on reasonable request. www.nature.com/scientificreports/